As the demand for semiconductor devices increases the need for improved handling of semiconductor characterization data also increases. Wafer inspection data is commonly acquired via optical inspection tools from one or more wafer processing tools of semiconductor device fabrication lines. This acquired inspection data may be used to track the quality of fabricated semiconductor devices at each step of the semiconductor device production process, allowing a user to reject sub-standard devices and/or adjust the fabrication process in order to bring subsequently process devices within a selected tolerance level. The volume of wafer processing is generally very large and in-line inspection tools must accommodate wafers moving at speed.
In all systems (tools) used for defect detection and defect classification the wafer is aligned to one or both axes of the stage prior to making any measurements on the wafer. To be able to align the wafer, pattern matching is performed between a unique feature in the field of view and a template saved in the recipe.
To be able to perform a successful pattern match between a template and a unique feature on a wafer that is in the field-of-view, the stage should not be in motion and the wafer should be in focus so that a good quality image can be acquired. Stage motion and focusing the wafer are typically done sequentially.
Images collected when stage move is still in progress or is settling after the end of a move have both motion and focus blur. Such images cannot be used for pattern matching.
Consequently, it would be advantageous if an apparatus existed that is suitable for removing motion and focus blur from wafer inspection images.